Ink set, ink jet recording method, recorded matter, and ink jet recording apparatus

ABSTRACT

An ink set includes an oil-based ink composition containing a metallic pigment; and at least one oil-based ink composition selected from the group consisting of a chromatic color ink composition containing a chromatic color oil dye, a black ink composition containing a black oil dye, and a colorless and transparent ink composition that does not contain a colorant.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. Ser. No. 12/497,730filed on Jul. 6, 2009, which claims priority to Japanese PatentApplication No. 2008-178021 filed on 8 Jul. 2008; the contents of whichare hereby incorporated by reference into the present application.

BACKGROUND

1. Technical Field

The present invention relates to an ink set, an ink jet recordingmethod, a recorded matter recorded by the ink jet recording method, andan ink jet recording apparatus. In particular, the invention relates toan ink set, an ink jet recording method, a recorded matter recorded bythe ink jet recording method, and an ink jet recording apparatus inwhich a printed surface having a metallic gloss of any color tone can beformed.

2. Related Art

Hitherto, in order to form a printed surface having a metallic gloss ona printed matter, a printing method using a printing ink containing agold powder or a silver powder which is prepared from brass particles,aluminum particles, or the like as a pigment, a foil stamping printingmethod using a metal foil, a thermal transfer method using a metal foil,or the like has been employed.

However, as for a printed surface obtained by using a printing inkcontaining a gold powder or a silver powder, the average particlediameter of a metal powder used is large; in the range of 10 to 30 μm,and thus matte metallic gloss can be obtained but it is difficult toobtain specular gloss. Meanwhile, in the foil stamping printing methodor the thermal transfer method in which a metal foil is used, anadhesive is applied to a printing medium, and a flat and smooth metalfoil is pressed thereon, or a recording medium is brought into closecontact with a metal foil and heated to thermally fusion-bond the metalfoil to the recording medium. Therefore, relatively good gloss can beobtained, but a special apparatus is necessary. Furthermore, the numberof steps in the production increases, and pressure or heat is appliedduring the production steps. Accordingly, the recording medium islimited to, for example, a recording medium that is resistant againstheat and deformation.

Recently, a large number of applications of ink jet in printing havebeen developed. An application thereof is a metallic printing. Forexample, JP-A-2002-179960 discloses a technique in which a metal coatingfilm is formed on the surfaces of spherical plastic particles, and anink composition containing the resulting pigment is printed by ink jetprinting. However, in order to obtain high metallic gloss, it isnecessary that the spherical particles be deformed to be flat so thatthe surfaces of the spherical particles become smooth. According to thistechnique, it is necessary to perform a pressing treatment with a rollerand a heat treatment at the same time. Accordingly, it is inevitablethat an apparatus and a production process are complicated in thisrespect, and the recording medium is also limited.

Furthermore, JP-A-2003-292836 and JP-A-2003-306625 disclose techniquesusing an ink composition in which a colloid of a noble metal such asgold or silver is dispersed. However, when the particle diameter of sucha noble metal colloid is decreased to several nanometers to several tensof nanometers so as to give a priority to dispersion stability, coloringdue to plasmon absorption occurs and metallic gloss for an inkcomposition cannot be obtained. In such a case, metallic gloss can beobtained by drying a printed surface, and then performing a heattreatment at 150° C. or higher to fusion-bond colloidal particles. Onthe other hand, when the particle diameter is increased in order to givea priority to metallic gloss, dispersion stability decreases, and thusproblems such as aggregation and precipitation inevitably occur.Consequently, the storage life of the ink composition significantlydecreases. In addition, obviously, using a noble metal as a materialsignificantly increases the cost of the ink composition, and such an inkcomposition is used only for a high-value added application, which isdisadvantageous in terms of the cost.

Furthermore, regarding a known metallic ink composition, a metallicpigment is mixed with a colorant, and the mixture is used as an inkcomposition. In this method, the metallic pigment and the colorant areseparated from each other during printing, or only the metallic pigmentprecipitates and aggregates during the storage of the ink composition.Such a problem may result in printing defects such as color loss inwhich only the colorant is absorbed in a recording medium and only themetallic pigment remains on a surface, and the formation of anon-uniform image having unevenness.

In addition, the method in which a metallic pigment is mixed with acolorant and the resulting mixture is used as an ink composition has aproblem that the expression of a metallic color is limited. For example,it is very difficult to express silver using an ink composition preparedby adding a yellow pigment to a metallic pigment so as to express gold.Accordingly, a method in which an ink composition containing only ametallic pigment is combined with a chromatic color ink compositioncontaining any colorant is more preferable because any metallic colorcan be efficiently expressed in a large number of combinations.

SUMMARY

An advantage of some aspects of the invention is to provide an ink setthat can form a printed surface having a metallic gloss with any colortone on a printed matter by focusing an attention to aluminum as arelatively inexpensive metal material, and constituting an ink setincluding an ink composition having high metallic specular gloss.

The inventors of the invention have conducted intensive studies andfound that a printed matter having high specular glossiness, which hasnot been realized to date, can be obtained by using an oil-based inkcomposition containing a specific metallic pigment.

In addition, the inventors of the invention found the following: When adye is used as a colorant, good transparency can be obtained and thegeneration of diffused light due to irregular reflection can besuppressed, as compared with the case where a pigment is used as acolorant. Accordingly, a dye is more preferably used when alight-transmissive recording medium is used. FIG. 1 shows an examplethat specifically illustrates this finding. FIG. 1 shows a distributionof the lightness (L* value) of transmitted light in the L*a*b* colorsystem in the case where a solid printing is performed on a transparentfilm using a dye or pigment of a yellow colorant, and respectiveapproximate a* value and b* value (ΔE=√(a*)²−(b*)²) thereof areprovided, and ΔE=1.2. FIG. 1 is a graph showing a profile of theintensity of transmitted light for every 5 degrees in a direction of−80° to +80° when light is incident from a 0° direction. In FIG. 1, theintensity of the transmitted light is plotted with respect to the Yvalue (lightness) in the XYZ color system and the L* value in the L*a*b*color system. As shown in FIG. 1, in the case where the pigment is usedas the colorant, a larger amount of light is diffused in directionsother than the 0° direction, which is the incident direction of light,as compared with the case where the dye is used as the colorant. In thecase of the pigment, opacity is confirmed even by visual observation,and a whitish color is observed.

On the basis of the above finding, the inventors of the invention havefound the following: In order to obtain a printed matter having ametallic gloss of any color tone, an ink set includes an oil-based inkcomposition containing a specific metallic pigment for forming metallicglossiness and an ink composition for forming the color tone, whereinthe ink composition for forming the color tone is an oil-based inkcomposition containing an oil dye as a colorant or an oil-based inkcomposition not containing a colorant. In this case, a printed matterhaving metallic glossiness of any color tone in which the colorant doesnot interfere with the metallic glossiness and transparency is improvedcan be formed, as compared with a case where an oil-based inkcomposition containing a pigment is used. This finding led to therealization of the invention.

According to a first aspect of the invention, an ink set includes anoil-based ink composition containing a metallic pigment; and at leastone oil-based ink composition selected from the group consisting of achromatic color ink composition containing a chromatic color oil dye, ablack ink composition containing a black oil dye, and a colorless andtransparent ink composition that does not contain a colorant.

Preferably, the ink set further includes a white oil ink compositioncontaining a white pigment.

In the ink set, the metallic pigment is preferably composed ofplate-like particles. When the major axis of the plate-like particles ina plane thereof is represented by X, the minor axis thereof isrepresented by Y, and the thickness thereof is represented by Z, a 50%average particle diameter R50 of an equivalent circle diameterdetermined by the area of the X-Y plane of the plate-like particles ispreferably in the range of 0.5 to 3 μm. Furthermore, the metallicpigment preferably satisfies the relationship R50/Z>5.

The metallic pigment is preferably composed of aluminum or an aluminumalloy.

The metallic pigment is preferably prepared by crushing a metalvapor-deposited film.

Preferably, the oil-based ink composition containing a metallic pigmentfurther contains an organic solvent and a resin.

The oil-based ink composition containing a metallic pigment preferablycontains the metallic pigment in an amount in the range of 0.1 to 10.0mass percent.

The organic solvent preferably contains at least one alkylene glycolether which is liquid at room temperature and atmospheric pressure.

The organic solvent is preferably a mixture of an alkylene glycoldiether, an alkylene glycol monoether, and a lactone.

The resin is preferably at least one selected from the group consistingof polyvinyl butyral, cellulose acetate butyrate, polyacrylic polyols,polyurethanes, vinyl chloride-vinyl acetate copolymers, and resinemulsions thereof.

Preferably, the oil-based ink composition containing a metallic pigmentfurther contains at least one selected from acetylene glycol surfactantsand silicone surfactants.

According to a second aspect of the invention, an ink jet recordingmethod includes ejecting droplets of an ink composition to cause thedroplets to adhere to a recording medium having an ink-accepting layer,wherein an image is formed using the ink set according to the firstaspect of the invention.

In this case, an image may be formed by ejecting the oil-based inkcomposition containing a metallic pigment, and at least one oil-basedink composition selected from the group consisting of the chromaticcolor ink composition, the black ink composition, and the colorless andtransparent ink composition at the same time.

Alternatively, an image may be formed using the oil-based inkcomposition containing a metallic pigment, and an image may then beformed using at least one oil-based ink composition selected from thegroup consisting of the chromatic color ink composition, the black inkcomposition, and the colorless and transparent ink composition.

Alternatively, an image may be formed using at least one oil-based inkcomposition selected from the group consisting of the chromatic colorink composition, the black ink composition, and the colorless andtransparent ink composition, and an image may then be formed using theoil-based ink composition containing a metallic pigment.

In the method, the recording medium is preferably a visiblelight-transmissive recording medium.

In the method, printing is preferably performed while heating therecording medium before printing and/or during printing and/or afterprinting.

In this case, the heating temperature is preferably in the range of 30°C. to 80° C.

A third aspect of the invention provides a recorded matter recorded bythe ink jet recording method according to the second aspect of theinvention.

According to a fourth aspect of the invention, an ink jet recordingapparatus includes the ink set according to the first aspect of theinvention.

According to a fifth aspect of the invention, in an image recordingmethod for forming an image using the ink set according to the firstaspect of the invention, the method includes a color image-forming stepof forming a color image in an ink-accepting layer provided on a visiblelight-transmissive recording medium using at least one oil-based inkcomposition selected from the group consisting of the chromatic colorink composition, the black ink composition, and the colorless andtransparent ink composition; and a metallic gloss image-forming step offorming a metallic gloss image on a surface of the visiblelight-transmissive recording medium, the surface opposite the surfacehaving the ink-accepting layer thereon, using the oil-based inkcomposition containing a metallic pigment.

According to a sixth aspect of the invention, in an image recordingmethod for forming an image using the ink set according to the firstaspect of the invention, the method includes a color image-forming stepof forming a color image in an ink-accepting layer provided on a visiblelight-transmissive recording medium using at least one oil-based inkcomposition selected from the group consisting of the chromatic colorink composition, the black ink composition, and the colorless andtransparent ink composition; and a metallic gloss image-forming step offorming a metallic gloss image on a visible light-transmissive orvisible light non-transmissive recording medium using the oil-based inkcomposition containing a metallic pigment, wherein the visiblelight-transmissive recording medium having the color image thereon andthe visible light-transmissive or visible light non-transmissiverecording medium having the metallic gloss image thereon are stacked sothat the color image and the metallic gloss image are in contact witheach other or the color image and the metallic gloss image are disposed,with one of the visible light-transmissive recording media therebetween.

According to an ink set, an ink jet recording method, a recorded matterrecorded by the ink jet recording method, and an ink jet recordingapparatus according to some aspects of the invention, by using an inkcomposition containing a metallic pigment, an image having high metallicgloss can be formed on a recording medium. Furthermore, an ink set isconstituted by combining the ink composition containing a metallicpigment with at least one oil-based ink composition selected from thegroup consisting of a chromatic color ink composition containing achromatic color oil dye, a black ink composition containing a black oildye, and a colorless and transparent ink composition that does notcontain a colorant, thereby forming an image that has not been realizedwith a known ink set, that is, an image having metallic glossiness ofany color tone in which the colorant does not interfere with themetallic glossiness and transparency is improved.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanyingdrawings, wherein like numbers reference like elements.

FIG. 1 is a graph showing a profile of the intensity of transmittedlight for every 5 degrees in a direction of −80° to +80° when printingis performed using a pigment or a dye and light is incident from a 0°direction, the intensity of the transmitted light being plotted withrespect to the Y value (lightness) in the XYZ color system and the L*value in the L*a*b* color system.

FIG. 2 is a schematic cross-sectional view of a recorded matter obtainedby forming an image on a visible light-transmissive recording mediumhaving an ink-accepting layer using an ink set of the invention.

FIG. 3 is an exploded perspective view illustrating the structure of arecording head.

FIG. 4 is a cross-sectional view illustrating the structure of an inkintroduction needle.

FIG. 5 is a schematic cross-sectional view showing an example of amethod of forming an image using an ink set of the invention.

FIGS. 6A and 6B are schematic cross-sectional views each showing anexample of a method of forming an image using an ink set of theinvention.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Ink Set

As described above, an ink set of the invention includes an oil-basedink composition containing a metallic pigment, and at least oneoil-based ink composition selected from the group consisting of achromatic color ink composition containing a chromatic color oil dye, ablack ink composition containing a black oil dye, and a colorless andtransparent ink composition that does not contain a colorant.Accordingly, an image to which a metallic gloss is added to color tonesof the chromatic color oil dye, the black oil dye, and the colorless andtransparent ink can be formed. In particular, since the ink set of theinvention includes a dye colorant, the colorant does not interfere withmetallic glossiness as compared with a pigment colorant, and an image towhich a metallic gloss of any color tone is added and which has hightransparency can be formed.

The metallic pigment is composed of plate-like particles. As for themetallic pigment, when the major axis of the plate-like particles in aplane thereof is represented by X, the minor axis thereof is representedby Y, and the thickness thereof is represented by Z, a 50% averageparticle diameter R50 of an equivalent circle diameter determined by thearea of the X-Y plane of the plate-like particles is preferably in therange of 0.5 to 3 μm, and the relationship R50/Z>5 is satisfied. Notethat the 50% average particle diameter R50 of the equivalent circlediameter determined by the area of the X-Y plane of the plate-likeparticles represents a number-average 50% average particle diameter.

The term “plate-like particle” refers to a particle having asubstantially flat planar (X-Y plane) shape and a substantially uniformthickness (Z). Since plate-like particles are prepared by crushing ametal vapor-deposited film, metal particles having a substantially flatplanar shape and a substantially uniform thickness can be obtained.Accordingly, the major axis of the plate-like particles in the planethereof, the minor axis thereof, and the thickness thereof can bedefined as X, Y, and Z, respectively.

The term “equivalent circle diameter” is the diameter when thesubstantially flat planar (X-Y plane) shape of a plate-like particle ofa metallic pigment is assumed to be a circle having the same projectedarea as a projected area of the particle of the metallic pigment. Forexample, when the substantially flat planar (X-Y plane) shape of aplate-like particle of a metallic pigment is a polygon, a projectionplane of the polygon is converted to a circle, and the diameter of thecircle is referred to as an equivalent circle diameter of the plate-likeparticle of the metallic pigment.

The 50% average particle diameter R50 of the equivalent circle diameterdetermined by the area of the X-Y plane of the plate-like particles ispreferably in the range of 0.5 to 3 μm, and further preferably in therange of 0.75 to 2 μm from the standpoint of metallic gloss and printstability.

As for the relationship between the 50% average particle diameter R50 ofthe equivalent circle diameter and the thickness Z, the relationshipR50/Z>5 is preferably satisfied from the standpoint that a high metallicgloss is ensured.

From the standpoint of the cost and the standpoint that a metallic glossis ensured, the metallic pigment is preferably composed of aluminum oran aluminum alloy. When an aluminum alloy is used, other metal elementsor non-metal elements that can be added to aluminum are not particularlylimited as long as the elements have a metallic gloss. Examples thereofinclude silver, gold, platinum, nickel, chromium, tin, zinc, indium,titanium, and copper. At least one of these elements, alloys thereof,and mixtures thereof is preferably used.

The metallic pigment is produced by, for example, the following method:First, a composite pigment base material having a structure in which aresin layer for detachment and a metal or alloy layer are sequentiallylaminated on a sheet-like substrate is prepared. The metal or alloylayer is detached from the sheet-like substrate at a boundary of aninterface between the metal or alloy layer and the resin layer fordetachment, and the detached metal or alloy layer is then crushed toform small particles. Thus, plate-like particles are obtained.Subsequently, when the major axis of the resulting plate-like particlesin a plane thereof, the minor axis thereof, and the thickness thereofare defined as X, Y, and Z, respectively, particles that have a 50%average particle diameter R50 of the equivalent circle diameterdetermined by the area of the X-Y plane of the plate-like particles inthe range of 0.5 to 3 μm and that satisfy the relationship R50/Z>5 arecollected.

The major axis X, the minor axis Y, and the equivalent circle diameterof the metallic pigment (plate-like particle) in a plane thereof can bemeasured with a particle image analyzer. As such a particle imageanalyzer, for example, a flow particle image analyzer FPIA-2100,FPIA-3000, or FPIA-3000S manufactured by Sysmex Corporation can be used.

The above-mentioned metal or alloy layer is preferably formed by vacuumevaporation, ion plating, or a sputtering method.

The metal or alloy layer is formed so as to have a thickness of 20 nm ormore and 100 nm or less. Consequently, a pigment having an averagethickness of 20 nm or more and 100 nm or less is obtained. Bycontrolling the thickness to be 20 nm or more, the resulting pigmentshas good reflectivity and brightness and thus has a high performance ofa metallic pigment. By controlling the thickness to be 100 nm or less,an increase in the apparent specific gravity is suppressed, anddispersion stability of the metallic pigment can be ensured.

The resin layer for detachment in the composite pigment base material,which is an undercoat layer of the metal or alloy layer, is a layer withdetachability for improving detachability from a surface of thesheet-like substrate. Preferable examples of a resin used in this resinlayer for detachment include polyvinyl alcohol, polyvinyl butyral,polyethylene glycol, polyacrylic acid, polyacrylamide, cellulosederivatives, acrylic acid polymers, and modified nylon resins.

A solution of one of the above resins or a mixture containing two ormore of the above resins is applied onto a sheet-like substrate, anddrying or the like is performed to form a layer. An additive such as aviscosity modifier may be incorporated in the application solution.

The resin layer for detachment is formed by a generally used applicationmethod such as gravure application, roll application, blade application,extrusion application, dip application, or a spin-coating method. Afterthe application and drying, the surface is planarized by a calendertreatment as required.

The thickness of the resin layer for detachment is not particularlylimited, but preferably in the range of 0.5 to 50 μm, and morepreferably in the range of 1 to 10 μm. If the thickness is less than 0.5μm, the amount of resin functioning as a dispersion resin isinsufficient. If the thickness exceeds 50 μm, in the case where theresin layer is formed into a roll, the resin layer is liable to detachfrom a pigment layer at the interface.

Examples of a material of the sheet-like substrate include, but are notlimited to, detachable films such as polytetrafluoroethylene,polyethylene, polypropylene, polyester films, e.g., polyethyleneterephthalate, polyamide films, e.g., 66 nylon and 6 nylon, apolycarbonate film, a triacetate film, and polyimide films. Thesheet-like substrate is preferably composed of polyethyleneterephthalate or a copolymer thereof.

The thickness of the sheet-like substrate is not particularly limited,but preferably in the range of 10 to 150 μm. When the thickness is 10 μmor more, problems do not occur in terms of handleability in producingsteps or the like. When the thickness is 150 μm or less, the sheet-likesubstrate has sufficient flexibility, and problems do not occur in termsof a formation of a roll, detachment, and the like.

As exemplified in JP-A-2005-68250, the metal or alloy layer may besandwiched between protective layers. Examples of the protective layersinclude a silicon oxide layer and a resin layer for protection.

The silicon oxide layer is not particularly limited as long as the layercontains silicon oxide. The silicon oxide layer is preferably formedfrom a silicon alkoxide such as tetraalkoxysilane or a polymer thereofby a sol-gel method.

An alcohol solution prepared by dissolving the silicon alkoxide or apolymer thereof is applied and baked by heating to form a silicon oxidecoating layer.

The resin layer for protection is not particularly limited as long as aresin that is insoluble in a dispersion medium is used. Examples of theresin include polyvinyl alcohol, polyethylene glycol, polyacrylic acid,polyacrylamide, and cellulose derivatives. The resin layer forprotection is preferably formed of polyvinyl alcohol or a cellulosederivative.

An aqueous solution of one of the above resins or a mixture containingtwo or more of the above resins is applied, and drying or the like isperformed to form a layer. An additive such as a viscosity modifier maybe incorporated in the application solution.

The application of silicon oxide or the resin is performed by the samemethod as the application of the resin layer for detachment describedabove.

The thickness of the protective layer is not particularly limited, butpreferably in the range of 50 to 150 nm. If the thickness is less than50 nm, the mechanical strength is insufficient. If the thickness exceeds150 nm, the strength becomes too high, and therefore it is difficult toperform crushing and dispersion and the protective layer may be detachedat the interface with the metal or alloy layer.

Furthermore, a colorant layer may be provided between the protectivelayer and the metal or alloy layer.

The colorant layer is provided in order to obtain any colored compositepigment. The colorant layer is not particularly limited as long as thecolorant layer can contain a colorant that can impart any color tone andhue in addition to the metallic gloss and brightness of the metallicpigment used in the invention. The colorant used in this colorant layermay be either a dye or a pigment. Known dyes and pigments may beappropriately used as the colorant.

In this case, the term “pigment” used in the colorant layer means anatural pigment, a synthetic organic pigment, a synthetic inorganicpigment, or the like as defined in the field of general pigmentchemistry and differs from a pigment that is processed into a laminatedstructure, for example, the “composite pigment” of the invention.

A method of forming the colorant layer is not particularly limited, butthe colorant layer is preferably formed by coating.

When the colorant used in the colorant layer is a pigment, preferably, aresin for dispersing the colorant is further incorporated. The resin fordispersing the colorant is preferably incorporated as follows in theform of a resin thin film: The pigment, the resin for dispersing thecolorant, as required, other additives, and the like are dispersed ordissolved in a solvent to form a solution. A uniform liquid film isformed by coating the solution and then dried to form a resin thin film.

Note that, in the production of the composite pigment base material,both the colorant layer and the protective layer are preferably formedby coating in terms of operation efficiency.

The composite pigment base material may have a layer configurationincluding a plurality of sequential laminated structure of the resinlayer for detachment and the metal or alloy layer. In such a case, thetotal thickness of the laminated structure including a plurality ofmetal or alloy layers, that is, the thickness of metal or alloylayer/resin layer for detachment/metal or alloy layer, or resin layerfor detachment/metal or alloy layer excluding the sheet-like substrateand the resin layer for detachment disposed directly on the substrate ispreferably 5,000 nm or less. When the thickness is 5,000 nm or less,even when the composite pigment base material is rounded to form a roll,cracking or detachment does not readily occur and the composite pigmentbase material can have satisfactory storage stability. In addition, whenthe composite pigment base material is formed into a pigment, theresulting pigment has good brightness, which is preferable.

Alternatively, the resin layer for detachment and the metal or alloylayer may be sequentially laminated on both surfaces of the sheet-likesubstrate. However, the structure of the composite pigment base materialis not limited thereto.

A method of detaching from the sheet-like substrate is not particularlylimited. However, preferable examples of the method include a method inwhich the composite pigment base material is immersed in a liquid, and amethod in which the composite pigment base material is immersed in aliquid and an ultrasonic treatment is performed at the same time toperform a detachment treatment and a crushing treatment of the detachedcomposite pigment.

According to the pigment obtained as described above, the resin layerfor detachment has a function of a protective colloid, and a stabledispersion liquid of the pigment can be prepared only by performing adispersion treatment in a solvent. Furthermore, in an ink compositioncontaining the pigment, the resin derived from the resin layer fordetachment also has a function of imparting adhesiveness to a recordingmedium such as paper.

An oil-based ink composition used in the ink set of the inventioncontains the metallic pigment described above, an organic solvent, and aresin.

The concentration of the metallic pigment in the ink composition ispreferably in the range of 0.1 to 10.0 mass percent.

When the concentration of the metallic pigment in the ink composition is0.1 mass percent or more and less than 1.5 mass percent, the followingprinting can be realized: By ejecting an ink in an amount with which aprinting surface is not sufficiently covered, a half-mirror-like glossysurface, more specifically, a texture in which glossiness can beprovided but the background is also seen through the glossiness can beformed by printing. By ejecting an ink in an amount with which aprinting surface is sufficiently covered, a metallic highly glossysurface can be formed. Therefore, such an ink composition is suitablyused, for example, when a half-mirror image is formed on a transparentrecording medium or when a metallic highly glossy surface is expressed.When the concentration of the metallic pigment in the ink composition is1.5 mass percent or more and 3.0 mass percent or less, the metallicpigment is arranged on a printing surface at random, and thus highglossiness is not obtained and matte metallic glossy surface can beformed. Therefore, such an ink composition is suitably used, forexample, when a shielding layer is formed on a transparent recordingmedium.

Preferable examples of the organic solvent that can be used includepolar organic solvents such as alcohols (e.g., methyl alcohol, ethylalcohol, propyl alcohol, butyl alcohol, isopropyl alcohol, andfluorinated alcohols); ketones such as (acetone, methyl ethyl ketone,and cyclohexanone); carboxylic acid esters (e.g., methyl acetate, ethylacetate, propyl acetate, butyl acetate, methyl propionate, and ethylpropionate); and ethers (e.g., diethyl ether, dipropyl ether,tetrahydrofuran, and dioxane).

In particular, the organic solvent preferably contains one or morealkylene glycol ethers which are liquid at room temperature andatmospheric pressure.

Alkylene glycol ethers include ethylene glycol ethers and propyleneglycol ethers based on aliphatic groups, such as methyl, n-propyl,i-propyl, n-butyl, i-butyl, hexyl, and 2-ethylhexyl groups; an allylgroup, which have a double bond; and a phenyl group. Such alkyleneglycol ethers have no color and little odor, have properties of both analcohol and an ether because of an ether group and a hydroxyl group intheir molecules, and are liquid at room temperature. These ethers aredivided into monoethers, in which one of the hydroxyl groups issubstituted, and diethers, in which the two hydroxyl groups aresubstituted. A plurality of these ethers may be used in combinations.

In particular, the organic solvent is preferably a mixture of analkylene glycol diether, an alkylene glycol monoether, and a lactone.

Examples of the alkylene glycol monoether include ethylene glycolmonomethyl ether, ethylene glycol monoethyl ether, ethylene glycolmonoisopropyl ether, ethylene glycol monobutyl ether, ethylene glycolmonohexyl ether, ethylene glycol monophenyl ether, diethylene glycolmonomethyl ether, diethylene glycol monoethyl ether, diethylene glycolmonobutyl ether, diethylene glycol dimethyl ether, diethylene glycoldiethyl ether, triethylene glycol monomethyl ether, triethylene glycolmonoethyl ether, triethylene glycol monobutyl ether, tetraethyleneglycol monomethyl ether, tetraethylene glycol monoethyl ether, propyleneglycol monomethyl ether, propylene glycol monoethyl ether, dipropyleneglycol monomethyl ether, and dipropylene glycol monoethyl ether.

Examples of the alkylene glycol diether include ethylene glycol dimethylether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether,diethylene glycol dimethyl ether, diethylene glycol diethyl ether,diethylene glycol dibutyl ether, triethylene glycol dimethyl ether,triethylene glycol diethyl ether, triethylene glycol dibutyl ether,tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether,tetraethylene glycol dibutyl ether, propylene glycol dimethyl ether,propylene glycol diethyl ether, dipropylene glycol dimethyl ether, anddipropylene glycol diethyl ether.

Examples of the lactone include γ-butyrolactone, δ-valerolactone, andε-caprolactone.

According to such a preferable configuration, the advantage of someaspects of the invention can be more effectively achieved.

Examples of the resin used in the oil-based ink composition includeacrylic resins, styrene-acrylic resins, rosin-modified resins, terpeneresins, polyester resins, polyamide resins, epoxy resins, vinyl chlorideresins, vinyl chloride-vinyl acetate copolymers, cellulose resins (e.g.,cellulose acetate butyrate and hydroxypropyl cellulose), polyvinylbutyral, polyacrylic polyols, polyvinyl alcohol, and polyurethanes.

Non-aqueous emulsion of polymer fine particles (non-aqueous dispersion(NAD)) may also be used as the resin. The non-aqueous dispersion (NAD)is a dispersion liquid in which fine particles composed of apolyurethane resin, an acrylic resin, an acrylic polyol resin, or thelike are stably dispersed in an organic solvent. Examples of thepolyurethane resin include Sanprene IB-501 and Sanprene IB-F370,manufactured by Sanyo Chemical Industries, Ltd. An example of theacrylic polyol resin is N-2043-60MEX manufactured by Harima Chemicals,Inc.

In order to further improve an adhesion property of the pigment to arecording medium, the resin emulsion is preferably added to the inkcomposition in an amount of 0.1 mass percent or more and 10 mass percentor less. If the amount added is too large, print stability is notprovided. If the amount added is too small, the adhesion property isinsufficient.

In particular, the resin is preferably at least one selected from thegroup consisting of polyvinyl butyral, cellulose acetate butyrate,polyacrylic polyols, polyurethanes, vinyl chloride-vinyl acetatecopolymers, and resin emulsions thereof.

The ink composition preferably contains at least one of glycerol,polyalkylene glycols, and saccharides. The total amount of at least oneof glycerol, polyalkylene glycols, and saccharides in the inkcomposition is preferably 0.1 mass percent or more and 10 mass percentor less.

According to such a preferable configuration, ejection of ink can bestabilized while suppressing drying of the ink and preventing clogging,thus realizing a satisfactory image quality of a recorded matter.

Polyalkylene glycols are linear polymer compounds having a repeatedstructure of ether bonds in their main chains and are produced by, forexample, ring-opening polymerization of cyclic ethers.

Specific examples of the polyalkylene glycol include polymers such aspolyethylene glycol and polypropylene glycol; ethylene oxide-propyleneoxide copolymers; and derivatives thereof. Any type of copolymer such asa random copolymer, a block copolymer, a graft copolymer, or analternating copolymer can be used.

A preferred specific example of the polyalkylene glycol is representedby the following formula:

HO—(C_(n)H_(2n)O)_(m)—H

(wherein n represents an integer of 1 to 5 and m represents an integerof 1 to 100).

In (C_(n)H_(2n)O)_(m) of the above formula, the integer n may be eithera single constant or a combination of two or more constants within theabove range. For example, when n is 3, the formula gives (C₃H₆O)_(m),and when n is a combination of 1 and 4, the formula gives(CH₂O—C₄H₈O)_(m). Also, the integer m may be either a single constant ora combination of two or more constants within the above range. Forexample, when m is a combination of 20 and 40 in the above example, theformula gives (CH₂O)₂₀—(C₄H₈O)₄₀, and when m is a combination of 10 and30, the formula gives (CH₂O)₁₀—(C₄H₈O)₃₀. Furthermore, any combinationof the integers n and m may be selected within the above ranges.

Examples of the saccharides include monosaccharides such as pentoses,hexoses, heptoses, and octoses; polysaccharides such as disaccharides,trisaccharides, and tetrasaccharides; and derivatives thereof such asreduced derivatives, e.g., as sugar alcohols and deoxy sugars, oxidizedderivatives, e.g., aldonic acids and uronic acids, dehydratedderivatives, e.g., glycoseens; amino sugars, and thio sugars. The term“polysaccharides” refers to sugars in a broad sense, and polysaccharidesinclude widely naturally occurring substances such as alginic acid,dextrin, and cellulose.

The oil-based ink composition preferably contains at least one selectedfrom acetylene glycol surfactants and silicone surfactants. Thesurfactant is preferably added in an amount of 0.01 mass percent or moreand 10 mass percent or less of the content of the pigment in the inkcomposition.

According to such a preferable configuration, wettability of theoil-based ink composition on a recording medium can be improved, thusrealizing a quick adhesion property.

Preferred examples of the acetylene glycol surfactants include Surfynol465 (trademark) and Surfynol 104 (trademark) (trade names, manufacturedby Air Products and Chemicals, Inc.) and Olfine STG (trademark) andOlfine E1010 (trademark) (trade names, manufactured by Nissin ChemicalIndustry Co., Ltd.).

As the silicone surfactant, polyester-modified silicone orpolyether-modified silicone is preferably used. Specific examples of thesilicone surfactants include BYK-347, BYK-348, BYK-UV3500, BYK-UV3510,BYK-UV3530, and BYK-UV3570 (manufactured by BYK Japan K.K.).

The oil-based ink composition can be prepared by a commonly used method.For example, first, the metallic pigment, a dispersant, and the solventare mixed, and a pigment dispersion liquid is then prepared using a ballmill, a bead mill, ultrasonic waves, a jet mill, or the like so that thepigment dispersion liquid has desired ink properties. Subsequently, abinder resin, the solvent, and other additives (such as a dispersion aidand a viscosity modifier) are added under stirring. Thus, the pigmentink composition can be obtained.

Alternatively, the composite pigment base material may be subjected toan ultrasonic treatment in a solvent to prepare a composite pigmentdispersion liquid, and the composite pigment dispersion liquid may thenbe mixed with a desired solvent for ink. Alternatively, the compositepigment base material may be subjected to an ultrasonic treatmentdirectly in a solvent for ink to prepare the ink composition withoutfurther treatment.

Although the physical properties of the oil-based ink composition arenot particularly limited, for example, the oil-based ink compositionpreferably has a surface tension of 20 to 50 mN/m. If the surfacetension is less than 20 mN/m, it may be difficult to eject ink dropletsbecause the ink composition wets and spreads on the surface of a head ofan ink jet recording printer or exudes on the surface. If the surfacetension exceeds 50 mN/m, satisfactory printing may not be performedbecause the ink composition does not wet and spread on the surface of arecording medium.

Next, a description will be made of color oil-based ink compositions,i.e., a chromatic color ink composition, a black ink composition, and acolorless and transparent ink composition that does not contain acolorant, all of which are used in an ink set of the invention. The term“chromatic color” refers to any color other than a series of colorsranging from white to black through gray (achromatic colors).

Each of the chromatic color ink composition and the black inkcomposition contains an oil dye (i.e., oil-soluble dye) as a colorant.The oil dye that can be used in the invention refers to a dye that issatisfactorily dissolved in liquid compounds other then water and thatis substantially insoluble in water under an environment of roomtemperature and atmospheric pressure. Oil dyes having a solubility towater (the weight of a dye that is soluble in 100 g of water) at 25° C.of 1 g or less can be used. The molecules of such an oil dye aredissolved in the ink composition to form a single molecule or a verysmall aggregate (having a diameter of about several tens of nanometers)in which several molecules gather together.

Specific examples of chromatic color oil dyes will be described below.In the description of specific examples below, the oil dyes are broadlyclassified into blue dyes, red dyes, and yellow dyes. Medium color dyes,namely, green dyes and violet dyes will also be described in the groupsof the above classification. Examples of the blue oil dyes includeindoaniline dyes; indophenol dyes; azomethine dyes containing apyrrolotriazole derivative as a coupling component; polymethine dyessuch as cyanine dyes, oxonol dyes, and merocyanine dyes; carbonium dyessuch as diphenylmethane dyes, triphenylmethane dyes, and xanthene dyes;phthalocyanine dyes; anthraquinone dyes; aryl dyes and heterylazo dyesall of which contain a phenol derivative, a naphthol derivative, or ananiline derivative as a coupling component; and indigo/thioindigo dyes.Specific examples of the blue oil dyes include Macrolex Blue RR and FR(manufactured by Bayer), Sumiplast Green G (manufactured by SumitomoChemical Co., Ltd.), Vali Fast Blue 2606, Oil Blue BOS (manufactured byOrient Chemical Industries Ltd.), Aizen Spilon Blue GNH (manufactured byHodogaya Chemical Co., Ltd.), Neopen Blue 808, Neopen Blue FF4012,Neopen Cyan FF4238 (manufactured by BASF Ltd.), Oil Violet #730(manufactured by Orient Chemical Industries Ltd.), C.I. Solvent Blue-2,-11, -25, -35, -38, -43, -67, -70, and -134, C.I. Solvent Green-1, -3,-7, -20, and -33, and C.I. Solvent Violet-2, -3, -11, and -47.

Examples of the red oil dyes include aryl dyes and heterylazo dyes allof which contain a phenol derivative, a naphthol derivative, or ananiline derivative as a coupling component; azomethine dyes containing apyrazolone derivative or a pyrazolotriazole derivative as a couplingcomponent; methine dyes such as arylidene dyes, styryl dyes, merocyaninedyes, and oxonol dyes; carbonium dyes such as diphenylmethane dyes,triphenylmethane dyes, and xanthene dyes; quinone dyes such asnaphthoquinone, anthraquinone, and anthrapyridone; and fused polycyclicdyes such as dioxazine dyes. Specific examples of the red oil dyesinclude Oil Red 5303 (manufactured by Arimoto Chemical Co., Ltd.), OilRed 5B, Oil Pink 312, Oil Scarlet 308 (manufactured by Orient ChemicalIndustries Ltd.), Oil Red XO (manufactured by Kanto Chemical Co., Inc.),Neopen Magenta SE1378 (manufactured by BASF Ltd.), Oil Brown GR(manufactured by Orient Chemical Industries Ltd.); C.I. Solvent Red-1,-3, -8, -18, -24, -27, -43, -49, -51, -72, -73, -109, -111, -229, -122,-132, and -219; C.I. Solvent Brown-1, -12, and -58; and ORACET RED BG(manufactured by Ciba Specialty Chemicals Inc.).

Examples of the yellow oil dyes include aryl dyes and heterylazo dyesall of which contain a phenol derivative, a naphthol derivative, ananiline derivative, a pyrazolone derivative, a pyridone derivative, oran open-chain active methylene compound as a coupling component.Examples thereof further include methine dyes such as azomethine dyes,benzylidene dyes, and monomethine oxonol dyes, and quinone dyes such asnaphthoquinone dyes and anthraquinone dyes all of which contain anopen-chain active methylene compound as a coupling agent. Furthermore,examples of yellow dyes other than the above dyes include quinophthalonedyes, nitro/nitroso dyes, acridine dyes, and acridinone dyes. Specificexamples of the yellow oil dyes include Oil Yellow 3G, Oil Yellow 129,Oil Yellow 105 (manufactured by Orient Chemical Industries Ltd.), FastOrange G, Neopen Yellow 075 (manufactured by BASF Ltd.), ORACET YELLOW3GN (manufactured by Ciba Specialty Chemicals Inc.), C.I. SolventYellow-1, -14, -16, -19, -25:1, -29, -30, -56, -82, -93, -162, and -172,and C.I. Solvent Orange-1, -2, -40:1, and -99.

Two or more of the above-mentioned dyes may be incorporated incombinations in the ink composition. When a plurality of dyes are usedin combination, some combinations may form achromatic colors.

Specific examples of the black oil dye will be described below. Specificexamples of the black dye include Sudan Black X60 (manufactured by BASFLtd.), Nubian Black PC-0850, Oil Black HBB (manufactured by OrientChemical Industries Ltd.), and C.I. Solvent Black-3, -7, -22:1, -27,-29, -34, and -50. Furthermore, the chromatic color ink composition mayfurther contain a black dye in order to, for example, adjust thelightness of the color of a chromatic color oil dye.

The content of the dye contained in the chromatic color ink compositionand the black ink composition is preferably in the range of 0.1 to 25mass percent, and more preferably in the range of 0.5 to 15 masspercent.

The colorless and transparent ink composition that does not contain acolorant (clear ink) has the same composition as the above chromaticcolor ink composition except that the colorless and transparent inkcomposition does not contain a colorant. Specifically, the colorless andtransparent ink composition contains a solvent and an adhesion resincomponent. The use of the colorless and transparent cleat ink can imparta function of protecting a metallic glossy surface formed by an adhesionof a metallic pigment.

The chromatic color ink composition, the black ink composition, and theclear ink may contain, as other components, known wetting agents,penetrants, pH adjusters, preservatives, fungicides, and the like.Furthermore, leveling additives, matte agents, and polyester resins,polyurethane resins, vinyl resins, acrylic resins, rubber resins, andwaxes for adjusting physical properties of a recorded matter may beoptionally added.

The chromatic color ink composition, the black ink composition, and theclear ink can be prepared by a known, commonly used method.

The ink set of the invention may include a white oil-based inkcomposition containing a white pigment as long as the advantages of theinvention is not impaired. By adding the white oil-based ink compositionto the ink set, a matte texture can be partly provided to a metallicglossy surface.

Examples of the white pigment include oxides of a Group IV element suchas titanium dioxide and zirconium dioxide. Examples thereof furtherinclude calcium carbonate, calcium sulfate, zinc oxide, barium sulfate,barium carbonate, silica, alumina, kaolin, clay, talc, white earth,aluminum hydroxide, magnesium carbonate, and a white hollow resinemulsion. Preferably, these white pigments are used alone or as amixture of two or more pigments selected from the group consisting ofthese pigments.

Hollow resin emulsions are oil-based dispersion liquids containinghollow polymer fine particles, wherein the hollow polymer fine particlesare composed of a plurality of fine particle subgroups, and regardingthe average particle size, a difference in the average particle diameterbetween fine particle subgroups adjacent to each other is less than 100nm.

The white pigment has a primary particle diameter preferably in therange of 0.02 to 1 μm, and more preferably in the range of 0.05 to 0.8μm in terms of whiteness. If the average particle diameter of the whitepigment particles exceeds 1 μm, for example, the white pigment particlesmay be precipitated, thereby impairing the dispersion stability. On theother hand, if the average particle diameter is less than 0.02 μm, thewhiteness tends to be insufficient.

Herein, the term “primary particle diameter” refers to the size of aparticle composed of aggregated single crystals or crystallitesequivalent thereto. The primary particle diameter of a pigment ismeasured by electron microscopy. In this method, the size of particlesof the pigment is measured using an electron micrograph. A more reliablevalue can be determined by dispersing the pigment in an organic solvent,immobilizing the pigment on a support film, and measuring the primaryparticle diameter from a transmission electron micrograph after imageprocessing. More specifically, the primary particle diameter isdetermined by measuring the minor axis and the major axis of the primaryparticles, calculating the diameters of circles having the same areas asthe primary particles as the primary particle diameters, and averagingthe primary particle diameters of 50 or more pigment particles selectedat random from a predetermined field of view. Any other method may beemployed as long as equivalent reliability is obtained, but the valuedetermined by the method described above is used if there is anysubstantial difference in measured values.

The content of the pigment in the white oil-based ink composition ispreferably 1.0 mass percent or more, more preferably 5.0 mass percent ormore, and further preferably 10 mass percent or more and 20 mass percentor less in terms of whiteness.

In addition to the pigment used as a colorant, the white oil-based inkcomposition preferably contains a dispersant for dispersing the pigment.Any dispersant that can be used for this type of pigment ink can be usedwithout particular limitations. Examples of the dispersant includecationic dispersants, anionic dispersants, nonionic dispersant, andsurfactants.

Examples of the anionic dispersant include polyacrylic acid,polymethacrylic acid, acrylic acid-acrylonitrile copolymers, vinylacetate-acrylate copolymers, acrylic acid-alkyl acrylate copolymers,styrene-acrylic acid copolymers, styrene-methacrylic acid copolymers,styrene-acrylic acid-alkyl acrylate copolymers, styrene-methacrylicacid-alkyl acrylate copolymers, styrene-α-methylstyrene-acrylic acidcopolymers, styrene-α-methylstyrene-acrylic acid-alkyl acrylatecopolymers, styrene-maleic acid copolymers, vinylnaphthalene-maleic acidcopolymers, vinyl acetate-ethylene copolymers, vinyl acetate-fatty acidvinylethylene copolymers, vinyl acetate-maleate copolymers, vinylacetate-crotonic acid copolymers, and vinyl acetate-acrylic acidcopolymers.

Examples of the nonionic dispersant include polyvinylpyrrolidone,polypropylene glycol, and vinylpyrrolidone-vinyl acetate copolymers.

Examples of the surfactant used as a dispersant include anionicsurfactants such as sodium dodecylbenzenesulfonate, sodium laurate, andammonium salts of polyoxyethylene alkyl ether sulfate; and nonionicsurfactants such as polyoxyethylene alkyl ethers, polyoxyethylene alkylesters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylenealkylphenyl ethers, polyoxyethylene alkylamines, and polyoxyethylenealkylamides. In particular, styrene-(meth)acrylic acid copolymers arepreferably used from the standpoint of enhancing dispersion stability ofthe pigment.

In the white oil-based ink composition, the same organic solvents,adhesion resin components, surfactants, and the like as those used inthe above-described oil-based ink composition containing a metallicpigment can be used as additives. The white oil-based ink compositionmay further contain other additives contained in typical oil-based inkcompositions. Examples of the additives include stabilizers such as anantioxidant and an ultraviolet absorber.

Examples of the antioxidant that can be used include2,3-butyl-4-oxyanisole (BHA) and 2,6-di-tert-butyl-p-cresol (BHT).Examples of the ultraviolet absorber that can be used includebenzophenone compounds and benzotriazole compounds.

The white oil-based ink composition can be prepared by a known, commonlyused method.

Ink Jet Recording Method

According to an ink jet recording method of the invention, an ink jetrecording method including ejecting droplets of an ink composition bydriving an ink jet head to cause the droplets to adhere to a recordingmedium, wherein an image is formed using the above-described ink set.

When the oil-based ink composition containing the above-mentioned metalpigment is used alone, it is possible to form images having a metallicgloss for which the measured values of specular glossiness at angles of20 degrees, 60 degrees, and 85 degrees specified in JIS Z8741 are 200 ormore, 200 or more, and 100 or more, respectively, at the same time. Byappropriately combining such images from the standpoint of angulardependency, images having a desired metallic gloss, i.e., from a matteimage to a glossy image, can be formed by using the oil-based inkcomposition.

More specifically, an image with a delustered (matte) metallic gloss canbe formed when the measured values of specular glossiness at angles of20 degrees, 60 degrees, and 85 degrees, which are specified in JISZ8741, are 200 or more and less than 400, 200 or more and less than 400,and 100 or more, respectively, at the same time.

In addition, a metallic gloss image on which a reflection of an objectcan be slightly seen can be formed when the measured values of specularglossiness at angles of 20 degrees, 60 degrees, and 85 degrees, whichare specified in JIS Z8741, are 400 or more and less than 600, 400 ormore and less than 600, and 100 or more, respectively, at the same time.

Furthermore, a sharp, metallic gloss image on which a reflection of anobject can be clearly seen, namely, a specular gloss image, can beformed when the measured values of specular glossiness at angles of 20degrees, 60 degrees, and 85 degrees, which are specified in JIS Z8741,are 600 or more, 600 or more, and 100 or more, respectively, at the sametime.

In contrast, in the case where the measured values of specularglossiness at angles of 20 degrees, 60 degrees, and 85 degrees are lessthan 200, less than 200, and less than 100, respectively, when such animage is visually observed, a metallic gloss is not provided and thecolor of the image is observed as gray. In addition, in the case whereany of the measured values of specular glossiness at angles of 20degrees, 60 degrees, and 85 degrees is less than the above specifiedvalue, the above-described metallic images cannot be obtained.

The amount of ink composition ejected onto the recording medium ispreferably in the range of 0.1 to 100 mg/cm², and more preferably 1.0 to50 mg/cm² from the standpoint that a metallic gloss is ensured and fromthe standpoints of the printing process and the cost.

The dry weight of the metallic pigment forming an image on the recordingmedium is preferably in the range of 0.0001 to 3.0 mg/cm² from thestandpoints of the metallic gloss, the printing process, and the cost. Ametallic glossy surface with high glossiness can be formed with asmaller dry weight of the metallic pigment. Accordingly, for example,this is suitable for a case where a half-mirror image is formed on avisible light-transmissive recording medium. A matte metallic glossysurface can be formed with a lager dry weight of the metallic pigment.Accordingly, for example, this is suitable for a case where a shieldinglayer is formed on a visible light-transmissive recording medium.

The oil-based ink composition containing a metallic pigment, and theoil-based ink composition (hereinafter also referred to as “oil-basedink composition for forming a color image”) containing the chromaticcolor ink composition, the black ink composition, and the colorless andtransparent ink composition that does not contain a colorant may beejected at the same time to form an image. Accordingly, a metallic glosscan be imparted to a chromatic color oil dye, a black oil dye, and acolorless and transparent color tone.

Alternatively, the oil-based ink composition containing a metallicpigment and the oil-based ink composition for forming a color image maybe separately ejected. In such a case, for example, an image having ametallic gloss may be formed using the oil-based ink compositioncontaining a metallic pigment and an image may then be formed using theoil-based ink composition for forming a color image. Alternatively, animage may be formed using the oil-based ink composition for forming acolor image and an image having a metallic gloss may then be formedusing the oil-based ink composition containing a metallic pigment.

The metallic pigment does not readily permeate an ink-accepting layer ona recording medium regardless of the presence or absence of anink-accepting layer on the recording medium, and therefore remainsadhered to the recording medium. In contrast, when the oil-based inkcomposition for forming a color image is ejected onto a recording mediumhaving an ink-accepting layer thereon, the dyes contained in the inkcomposition easily permeate the ink-accepting layer. Accordingly, evenwhen an image having a metallic gloss is formed using the oil-based inkcomposition containing a metallic pigment and an image is then formedusing the oil-based ink composition for forming a color image, the dyesin the oil-based ink composition for forming a color image permeate theink-accepting layer, and a metallic gloss image with any color tone canbe obtained. FIG. 2 is a schematic cross-sectional view of a recordedmatter obtained by forming an image on a visible light-transmissiverecording medium having an ink-accepting layer using an ink set of theinvention. By using a visible light-transmissive recording medium 1having an ink-accepting layer 2, a metallic gloss image with any colortone can be obtained while a dye 3, which is a colorant, does notinterfere with a metallic gloss of a metallic pigment-adhering layer 4functioning as an underlying layer, when an observation surface is thefilm layer 5 side of the visible light-transmissive recording medium 1.(In this method of forming an image, the image can be observed from theside opposite the printed surface.) In this case, the oil-based inkcomposition containing a metallic pigment and the oil-based inkcomposition for forming a color image may be ejected at the same time.Alternatively, an image having a metallic gloss may be formed using theoil-based ink composition containing a metallic pigment and an image maythen be formed using the oil-based ink composition for forming a colorimage. Alternatively, an image may be formed using the oil-based inkcomposition for forming a color image and an image having a metallicgloss may then be formed using the oil-based ink composition containinga metallic pigment. On the other hand, in the case where a recordingmedium not having an ink-accepting layer is used, a metallic gloss imagewith any color tone can be obtained by the method in which an imagehaving a metallic gloss is formed using the oil-based ink compositioncontaining a metallic pigment and an image is then formed using theoil-based ink composition for forming a color image.

Examples of a method of ejecting an ink composition include thefollowing methods.

A first method is an electrostatic attraction method. In this method, astrong electric field is applied between a nozzle and an acceleratingelectrode placed in front of the nozzle to successively eject an inkfrom the nozzle in the form of droplets, and a printing informationsignal is supplied to deflection electrodes while the ink dropletstravels between the deflection electrodes to conduct recording, or theink droplets are ejected so as to correspond to the printing informationsignal without deflecting the ink droplets.

In a second method, ink droplets are forcibly ejected by applying apressure to a liquid ink using a small pump and mechanically vibrating anozzle using a quartz oscillator or the like. The ejected ink dropletsare simultaneously charged during ejection, and a printing informationsignal is supplied to deflection electrodes while the ink dropletstravels between the deflection electrodes to conduct recording.

A third method is a method using a piezoelectric element (piezoelement). In this method, a pressure and a printing information signalare simultaneously applied to a liquid ink using the piezoelectricelement to eject and record ink droplets.

A fourth method is a method in which the volume of a liquid ink israpidly expanded by an action of thermal energy. In this method, aliquid ink is foamed by heating using a microelectrode in accordancewith a printing information signal to eject and record ink droplets.

Any of the above methods can be employed as the ink jet recording methodof the invention. However, from the standpoint of a high-speed printing,the method of ejecting an ink composition is preferably a method withoutheating. That is, the first method, the second method, or the thirdmethod is preferably employed.

Examples of the recording medium include, but are not particularlylimited to, various visible light-transmissive or visible lightnon-transmissive recording media such as plain paper, ink jet printingpaper (matte paper and gloss paper), glass, a film of a plastic such asvinyl chloride, a film in which a base material is coated with a plasticor an ink-accepting layer, a metal, and a printed wiring substrate.Examples of the ink-accepting layer include, but are not particularlylimited to, an acrylic resins and styrene-acrylic resins.

When the recording medium has an ink-accepting layer, printing ispreferably conducted without heating the recording medium from thestandpoint of avoiding thermal damage of the ink-accepting layer.

On the other hand, when the recording medium does not have anink-accepting layer, printing is preferably conducted while heating therecording medium from the standpoints of increasing the drying speed andobtaining high gloss.

The heating may be performed with a heat source being in contact with arecording medium, or with a heat source not being in contact with arecording medium, for example, irradiating the recording medium withinfrared rays or microwaves (electromagnetic waves having a maximumwavelength of approximately 2,450 MHz) or blowing hot air to therecording medium.

The heating is preferably performed before printing and/or duringprinting and/or after printing. That is, the heating of the recordingmedium may be performed before printing, during printing, afterprinting, or during the entire printing process. The heating temperatureis determined depending on the type of recording medium, and ispreferably in the range of 30° C. to 80° C. and more preferably in therange of 40° C. to 60° C.

Recording Apparatus

A recording apparatus of the invention is an ink jet recording apparatusincluding the ink set described above. Next, the structure a recordinghead 13 of the ink jet recording apparatus will be described. FIG. 3 isa schematic perspective view of the recording head 13 accommodated in acarriage (not shown). Furthermore, FIG. 4 is a cross-section view of anink introduction needle 19 to be inserted into an ink cartridge.

The recording head 13 shown as an example includes a cartridge base 15(hereinafter referred to as “base”). A head case 16 is attached to thebase 15. A flow channel unit 17 is attached to (provided on) a leadingend of the head case 16. The base 15 is formed by, for example, moldinga synthetic resin and a plurality of partitions 15′ (liquid storagemember-mounting portions) are provided on the top surface of the base15.

An ink introduction needle 19 is attached to each of the partitions 15′with a mesh filter 18 therebetween. An ink cartridge (not shown) ismounted on the partitions 15′. That is, the ink cartridge is disposed onthe base 15. The ink introduction needles 19 that are inserted into theink cartridge will be described in detail below. A circuit board 20 isattached to another surface of the base 15 opposite the partitions 15′.Furthermore, this circuit board 20 is attached to the base 15 with asheet member 21 functioning as a gasket therebetween.

The head case 16 is fixed to the base 15 and functions as a casing foraccommodating a vibrator unit 22 including a piezoelectric vibrator.Furthermore, a flow channel unit 17 is fixed, with an adhesive or thelike, to a leading end surface of the head case 16, the end surfaceopposite the surface on which the base 15 is mounted. This flow channelunit 17 is produced by sequentially staking an elastic plate 23, achannel-forming substrate 24, and a nozzle plate 25, and integrating theresulting product by fixing with an adhesive or the like.

The nozzle plate 25 is a plate-like member prepared from a thinstainless steel plate, and has fine nozzle openings 26 arranged in lineat a pitch corresponding to a dot-forming density of the printer.Furthermore, a head cover 27 is constituted by, for example, a thinplate member composed of a metal.

As shown in FIG. 4, the ink introduction needle 19 that is inserted intothe ink cartridge is a hollow needle which has a conical shape at a tipof the upstream side and in which an ink introduction path 41 isprovided inside thereof. The lower half portion of the ink introductionneedle 19 has a tapered shape diverging from the upstream side to thedownstream side. Furthermore, ink introduction holes 42 communicatingthe outside space with the ink introduction path 41 are provided at theleading end side of the ink introduction needle 19.

The ink introduction needle 19 is attached to the base 15 with the meshfilter 18 therebetween by, for example, ultrasonic welding. Accordingly,the ink introduction path 41 of the ink introduction needle 19communicates with an ink communication path 37 of the head case 16.

Furthermore, when the ink cartridge (not shown) is set in a partition15′ of the base 15, the ink introduction needle 19 is inserted into aneedle insertion opening of the ink cartridge, and an inside cavity ofthe ink cartridge communicates with the ink introduction path 41 in theink introduction needle 19, with the ink introduction holes 42therebetween. Next, the ink stored in the ink cartridge is introducedinto the ink introduction path 41 through the ink introduction holes 42,and ejected from the nozzle opening 26 through the ink communicationpath 37.

When the diameter of the nozzle opening 26 of the recording head 13 ofthe ink jet recording apparatus is L μm, and the size of the openings ofthe mesh filter 18 provided in the ink introduction path 41 is W μm, thenozzle diameter L μm and the size W μm of the openings of the meshfilter 18 preferably satisfy the relationship L≧5W. In the case where anink composition containing a metallic pigment dispersion liquid used inthe invention is used in an ink jet recording apparatus that satisfiesthis relationship, from the standpoints of preventing the nozzleopenings 26 from clogging with the metallic pigment and ensuringejection stability of the ink composition, the following condition ispreferably satisfied. Specifically, when the average particle diameterof the equivalent circle diameter determined by the area of the X-Yplane of the plate-like particles is R μm, the number of plate-likeparticles satisfying the relationship R>(L/5) is preferably 5% or lessof the total number of plate-like particles.

Method of Recording Image

In the invention, a metallic image (metallic gloss image) with any colortone can be formed by another method of forming an image using theabove-described ink set. For example, as shown in FIG. 5, on a surfaceof a visible light-transmissive recording medium 1 having anink-accepting layer 2, a desired image is formed in the ink-acceptinglayer 2 using an oil-based ink composition for forming a color image,and a metallic pigment-adhering layer 4 is formed using an oil-based inkcomposition containing a metallic pigment on a surface opposite thesurface having the ink-accepting layer 2 of the visiblelight-transmissive recording medium 1 thereon. Thus, a metallic glossimage with any color tone can be obtained while a dye 3, which is acolorant, does not interfere with a metallic gloss of the metallicpigment-adhering layer 4 functioning as an underlying layer when anobservation surface is the ink-accepting layer 2 side of the visiblelight-transmissive recording medium 1.

Alternatively, as shown in FIG. 6A, a visible light-transmissiverecording medium 1 on which a desired image is formed in anink-accepting layer 2 using an oil-based ink composition for forming acolor image and a visible light-transmissive or visible lightnon-transmissive recording medium 6 on which a desired image is formedusing an oil-based ink composition containing a metallic pigment may bestacked so that the color image and an adhering layer 4 of the metallicpigment are in contact with each other. Alternatively, as shown in FIG.63, such a visible light-transmissive recording medium 1 and such avisible light-transmissive or visible light non-transmissive recordingmedium 6 may be stacked so that the color image and an adhering layer 4of the metallic pigment are disposed, with one of the visiblelight-transmissive recording media 1 and 6 therebetween. Also in thesecases, a metallic gloss image with any color tone can be obtained whilea dye 3, which is a colorant, does not interfere with a metallic glossof the metallic pigment-adhering layer 4 functioning as an underlyinglayer.

Recorded Matter

A recorded matter of the invention is a matter recorded by the ink jetrecording method or the method of recording an image described aboveusing the above-described ink set. Since this recorded matter isobtained by the ink jet recording method or the method of recording animage using the above-described ink set, a recorded matter having ametallic image with any highly transparent color tone can be obtained.

EXAMPLES 1. Metallic Ink Composition (1) Preparation of Metallic PigmentDispersion Liquid

A resin coating solution containing 3.0 mass percent of celluloseacetate butyrate (butylation ratio: 35% to 39%, manufactured by KantoChemical Co., Inc.) and 97 mass percent diethylene glycol diethyl ether(manufactured by Nippon Nyukazai Co., Ltd.) was uniformly applied by abar-coating method onto a PET film having a thickness of 100 μm, andthen dried for 10 minutes at 60° C. to form a thin resin layer on thePET film.

Next, an aluminum vapor deposition layer having an average thickness of20 nm was formed on the resin layer using a vacuum deposition apparatus(vacuum deposition apparatus model VE-1010, manufactured by VacuumDevice Inc.).

Next, detachment, pulverization, and dispersion treatments of theresulting laminate formed by the above method were simultaneouslyperformed in diethylene glycol diethyl ether using a VS-150 ultrasonicdispersing device (manufactured by As One Corporation), thus preparing ametallic pigment dispersion liquid by ultrasonically dispersing for 12hours in total.

The resulting metallic pigment dispersion liquid was filtered using anSUS mesh filter with an opening size of 5 μm to remove coarse particles.Subsequently, the filtrate was poured into a round bottom flask, and thediethylene glycol diethyl ether was distilled off with a rotaryevaporator. Accordingly, the metallic pigment dispersion liquid wasconcentrated, and the concentration of the metallic pigment dispersionliquid was then adjusted. Thus, a metallic pigment dispersion liquidwith a concentration of 5 mass percent was obtained.

Furthermore, the 50% average particle diameter R50 of an equivalentcircle diameter determined by the area of the major axis (Xdirection)-minor axis (Y direction) plane of each of the metallicpigment particles, and the average film thickness Z were measured usinga particle diameter and particle size distribution analyzer (FPIA-3000Smanufactured by Sysmex Corporation), and R50/Z was calculated on thebasis of the measured values of R50 and Z. Note that a particle sizedistribution value (CV value) was determined by the equation CVvalue=standard deviation of the particle size distribution/averageparticle diameter×100. The results are shown in Table 1.

TABLE 1 50% Particle Average Metallic average size particle Averagepigment particle distribution diameter film dispersion diameter valueRmax thickness liquid R50 (μm) (CV value) (μm) Z (μm) R50/Z 1 1.03 44.04.9 0.02 51.5 2 1.43 48.9 6.9 0.02 71.5 3 2.54 47.2 7.2 0.02 127.0 41.13 44.8 5.9 0.02 56.5 5 1.02 48.4 5.7 0.03 34.0 6 0.91 45.1 4.2 0.0245.5 7 0.86 46.6 4.3 0.02 43.0 8 0.89 38.2 3.2 0.02 44.5 9 5.52 81.2 300.10 55.2 10 1.42 65.0 12 0.30 4.7 11 1.40 60.2 7.1 0.30 4.7

(2) Preparation of Metallic Pigment Ink Composition

Metallic pigment ink compositions having the compositions shown in Table2 were prepared using the metallic pigment dispersion liquids preparedby the method described above. Additives were mixed with and dissolvedin solvents to prepare ink solvents. Subsequently, the metallic pigmentdispersion liquids were added to the ink solvents, and each of theresulting mixtures was further blended and stirred with a magneticstirrer for 30 minutes at room temperature and atmospheric pressure.Thus, metallic pigment ink compositions were prepared.

Diethylene glycol diethyl ether (DEGDE), dipropylene glycol monobutylether (DPGMB), and tetraethylene glycol dimethyl ether (TEGDM)manufactured by Nippon Nyukazai Co., Ltd. were used as those shown inTable 2. Furthermore, γ-butyrolactone manufactured by Kanto ChemicalCo., Inc. was used. In addition, N-2043-AF-1 (resin emulsion)manufactured by Harima Chemicals Inc., and BYK-3500 (surfactant)manufactured by BYK Japan K.K. were used. Note that the units areexpressed in mass percent.

TABLE 2 Comparative Reference Ink Reference Examples Examplescomposition 1 2 3 4 5 6 7 8 1 2 3 DEGDE 47.8 47.8 47.8 61.8 61.8 61.861.8 61.8 47.8 47.8 47.8 DPGMB 45 45 45 45 45 45 γ-Butyrolactone 15 1515 15 15 TEGDM 18 18 18 18 18 N-2043-AF-1 6.0 6.0 6.0 4.0 4.0 4.0 4.04.0 6.0 6.0 6.0 BYK-3500 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2Pigment solid 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 content(Metallic pigment (1) (2) (3) (4) (5) (6) (7) (8) (9) (10) (11)dispersion liquid)

(3) Measurement of Glossiness

A black block was filled with an ink composition, and solid printing wasperformed using an ink jet printer EM-930C (manufactured by Seiko EpsonCorporation) at room temperature on photographic paper (glossy) havingan ink-accepting layer manufactured by the same company (Product number:KA450PSK). The amount of ink composition ejected at that time was 1.2mg/cm², and the dry weight of the metal pigment was 12 μg/cm². Theglossiness of the image obtained was measured using a glossmeter (MULTIGloss 268 manufactured by Konica Minolta Holdings, Inc.). The resultsare shown in Table 3.

The criterion for evaluation of the glossiness is as follows:

20° glossinessA: 300 or more (clear metallic gloss)B: 200 or more and less than 300 (matte metallic gloss)C: Less than 200 (no metallic gloss)60° glossinessA: 500 or more (clear metallic gloss)B: 300 or more and less than 500 (matte metallic gloss)C: Less than 300 (no metallic gloss)85° glossinessA: 120 or more (clear metallic gloss)B: 100 or more and less than 120 (matte metallic gloss)C: Less than 100 (no metallic gloss)

TABLE 3 Glossiness 20° 60° 85° glossiness glossiness glossinessReference Example 1 B B B Reference Example 2 A B B Reference Example 3B B B Reference Example 4 A A A Reference Example 5 A A A ReferenceExample 6 A A A Reference Example 7 A B A Reference Example 8 A A AComparative Reference — — — Example 1 Comparative Reference C B BExample 2 Comparative Reference A B B Example 3 —: Not detected

Referring to the results shown in Table 3, when metallic pigments havingan R50 in the range of 0.5 to 3 μm, and satisfying the relationshipR50/Z>5 are used, an image having a desired metal gloss ranging from amatte image to a gloss image can be formed.

2. Ink Set (1) Preparation of Metallic Ink Composition

Metallic pigment ink compositions having the compositions shown in Table4 were prepared using the metallic pigment dispersion liquid 4 preparedby the above method. Additives were mixed with and dissolved in solventsto prepare ink solvents. Subsequently, the metallic pigment dispersionliquid was added to each of the ink solvents, and each of the resultingmixtures was further blended and stirred with a magnetic stirrer for 30minutes at room temperature and atmospheric pressure. Thus, metallicpigment ink compositions (S1 and S2) were prepared.

Diethylene glycol diethyl ether (DEGDE) and tetraethylene glycoldimethyl ether (TEGDM) manufactured by Nippon Nyukazai Co., Ltd. wereused as those shown in Table 4. Furthermore, γ-butyrolactonemanufactured by Kanto Chemical Co., Inc. was used. In addition,N-2043-60MEX (polyacrylic polyol resin emulsion) manufactured by HarimaChemicals Inc., BYK-3500 (surfactant) manufactured by BYK Japan K.K.,and E-1010 (surfactant) manufactured by Nissin Chemical Industry Co.,Ltd. were used. Note that the units are expressed in mass percent.

TABLE 4 Metallic ink composition Ink composition S1 S2 DEGDE 61.8 61.0γ-Butyrolactone 15.0 15.0 TEGDM 18.0 18.0 N-2043-60MEX 4.0 4.0 BYK-35000.2 — E-1010 — 1.0 Pigment solid 1.0 1.0 content

(2) Preparation of Oil-Based Ink Composition for Forming Color Image(Chromatic Color Ink Composition, Black Ink Composition, Colorless andTransparent Ink (Clear Ink) Composition, and White Ink Composition)(2-1) Compositions of Dye Ink Compositions and Clear Ink Composition

A yellow ink composition, a magenta ink composition, a cyan inkcomposition, a black ink composition, and a clear ink composition havingthe compositions shown in Table 5 were prepared. Diethylene glycoldiethyl ether (DEGDE) and tetraethylene glycol dimethyl ether (TEGDM)manufactured by Nippon Nyukazai Co., Ltd. were used as those shown inTable 5. Furthermore, γ-butyrolactone (γ-BL) manufactured by KantoChemical Co., Inc. was used. In addition, N-2043-60MEX (polyacrylicpolyol resin emulsion) manufactured by Harima Chemicals Inc., andBYK-UV3500 (surfactant) manufactured by BYK Japan K.K. were used. Inaddition, various oil dyes manufactured by Ciba Specialty Chemicals Inc.were used. Note that, in Table 4, the units are expressed in masspercent.

(2-2) Method of Preparing Dye Ink Compositions and Clear Ink Composition

Additives were mixed with and dissolved in solvents to prepare inksolvents. Subsequently, dyes were added to the ink solvents, and each ofthe resulting mixtures was blended and stirred with a magnetic stirrerfor 30 minutes at room temperature and atmospheric pressure. Thus, dyeink compositions were prepared. In addition, a clear ink composition wasprepared by the same method except that no dye was used.

TABLE 5 Yellow Magenta Cyan Black Clear Y M C K CL DEGDE 61.8 61.8 61.861.8 62.8 γ-BL 15.0 15.0 15.0 15.0 15.0 TEGDM 18.0 18.0 18.0 18.0 18.0N-2043- 4.0 4.0 4.0 4.0 4.0 60MEX BYK-UV3500 0.2 0.2 0.2 0.2 0.2Colorant ORACET ORACET ORACET ORASOL — Yellow Red BG Blue G Black RLI3GN 1.0 1.0 1.0 1.0

(2-3) Composition of Pigment Ink Composition

A yellow ink composition, a magenta ink composition, a cyan inkcomposition, a black ink composition, and a white ink composition havingthe compositions shown in Tables 6 and 7 were prepared. Except for apigment component, the same additives shown in Table 5 were used in thewhite ink composition shown in Table 6. In Table 7, the “dispersant” isa polyester polymer compound, “N-2043-60MEX” is a polyacrylic polyolresin emulsion, the “mixed organic solvent” is a mixed solventcontaining diethylene glycol diethyl ether (70 mass percent),γ-butyrolactone (15 mass percent), and tetraethylene glycol dimethylether (15 mass percent). The pigments shown in Tables 6 and 7 are C.I.Pigment Yellow 213, Pigment Violet 19, Pigment Blue 15:3, and PigmentBlack 7. The numerical values in Tables 6 and 7 are expressed in masspercent.

The hollow resin emulsion in Table 7 was produced as follows.Hereinafter, unless otherwise stated, the term “parts” is calculated onthe basis of the mass.

[1] Polymer Particles 1

First, 80 parts of styrene, 5 parts of methacrylic acid, 15 parts ofmethyl methacrylate, 1 part of α-methylstyrene dimer, 14 parts oft-dodecyl mercaptan, 0.8 parts of sodium dodecylbenzenesulfonate, 1.0part of potassium persulfate, and 200 parts of water were placed in a2-L reaction vessel. The mixture was stirred in nitrogen gas, and heatedto 80° C. to conduct emulsion polymerization for 6 hours. Polymerparticles 1 thus obtained had an average particle diameter of 150 nm(0.15 μm).

[2] Hollow Polymer Fine Particle Emulsion 1

First, 10 parts (in terms of solid content) of Polymer particles 1obtained in [1] above, 0.3 parts of sodium lauryl sulfate, 0.5 parts ofpotassium persulfate, and 400 parts of water were placed in a reactionvessel. A cross-linking polymerizable monomer composition containing amixture of 11.6 parts of divinylbenzene (purity: 55 mass percent; theremainder is a monofunctional vinyl monomer), 8.4 parts ofethylvinylbenzene, 5 parts of acrylic acid, and 75 parts of methylmethacrylate was added to the reaction vessel. An emulsionpolymerization process was conducted while stirring the resultingmixture at 30° C. for one hour and further stirring at 70° C. for fivehours, thus obtaining an aqueous dispersion liquid. The particlediameter of the particles in the prepared dispersion liquid was measuredwith a particle size analyzer (Microtrac UPA, manufactured by NikkisoCo., Ltd.). According to the result, the particle diameter was 320 nm.Separately, the dispersion liquid was observed with a transmissionelectron microscope. It was confirmed that the dispersion liquidcontained hollow polymer fine particles.

(2-4) Method of Preparing Pigment Ink Composition

The pigment ink composition (W) shown in Table 6 was prepared asfollows.

[1] Method of Preparing Titanium Dioxide Fine Particles

A titanium-containing ore was dissolved with sulfuric acid to obtain atitanium sulfate solution. The titanium sulfate solution was hydrolyzedto obtain hydrous titanium oxide. Subsequently, 0.50 parts by mass ofammonium phosphate, 0.30 parts by mass of potassium sulfate, and 0.30parts by mass of aluminum sulfate were added to 100 parts by mass of thehydrous titanium oxide in terms of TiO₂. The hydrous titanium oxide washeated in a laboratory rotary muffle furnace until the temperature ofthe resulting product reached 1,020° C. Titanium dioxide fine particlesproduced were cooled to room temperature, and observed with atransmission electron micrograph. According to the result, it was foundthat the fine particles were anatase TiO₂ particles having an averageprimary particle diameter of 0.13 μm.

[2] Preparation of Dispersion Liquid of Titanium Dioxide Fine Particles

First, 15 parts by mass of the titanium dioxide fine particles servingas a surface-treated white pigment, 5 parts by mass of apolyoxyalkylene-added polyalkylene amine (DISCOL N-518, manufactured byDai-Ichi Kogyo Seiyaku Co., Ltd.) serving as a dispersant, and 80 partsby mass of diethylene glycol diethyl ether were mixed to prepare aslurry. Zirconia beads (1.0 mm diameter) were charged in an amount of1.5 times the amount of slurry and dispersed for two hours with a sandmill (manufactured by Yasukawa Seisakusho). The beads were then removedto obtain a dispersion liquid of the titanium dioxide fine particles.

[3] Preparation of White Ink Composition (W)

A white ink composition (W) was prepared using the dispersion liquid ofthe titanium dioxide fine particles so as to have the composition shownin Table 6. Specifically, diethylene glycol diethyl ether,γ-butyrolactone, tetraethylene glycol dimethyl ether, N-2043-60MEX, anda surfactant were placed in a vessel, and sufficiently mixed for 30minutes under stirring with a magnetic stirrer. The dispersion liquidwas added to the resulting mixture, and the mixture was further mixedunder stirring for one hour. The resulting product was filtered using a10 μm PTFE membrane filter to prepare the white ink composition (W).

The pigment ink compositions (Y1, M1, C1, B1, and W1) shown in Table 7were prepared as follows. First, among mixing components, a pigment, adispersant, and a (portion of) mixed organic solvent were stirred with adissolver at 3,000 rpm for one hour, and preliminary dispersion was thenperformed with a bead mill filled with zirconia beads (2 mm). Pigmentparticles obtained by this preliminary dispersion had an averageparticle diameter of 5 μm or less. Furthermore, dispersion was performedwith a nanomill filled with zirconia beads (0.3 mm) to prepare a pigmentdispersion liquid. The pigment particles obtained by this dispersion hadan average particle diameter in the range of 50 to 200 nm.

Subsequently, N-2043-60MEX, a typical additive, a hollow resin emulsion,and (the rest of) the mixed organic solvent were mixed while stirringthe pigment dispersion liquid at 4,000 rpm so that the amount of pigmentin terms of parts by mass was adjusted to the amount in terms of masspercent shown in the composition described above. Thus, desired inkcompositions (Y1, M1, C1, B1, and W1) were prepared.

TABLE 6 White W DEGDE 57.8 γ-BL 15.0 TEGDM 18.0 N-2043-60MEX 4.0BYK-UV3500 0.2 Colorant Titanium dioxide 5.0

TABLE 7 Yellow Magenta Cyan Black White Y1 M1 C1 B1 W1 PY213 6.0 — — — —PV19 — 6.0 — — — PB15:3 — — 3.0 — — PBk7 — — — 4.0 — Hollow resin — — —— 11.0 emulsion Dispersant 2.0 3.0 2.0 2.0 — N-2043- 4.0 4.0 4.0 4.0 5.060MEX BYK- 0.2 0.2 0.2 0.2 0.2 UV3500 Mixed Remainder RemainderRemainder Remainder Remainder organic solvent

(3) Ink Set

Ink sets including ink compositions in combinations shown in Table 8were prepared by using the metallic ink compositions obtained in (1)above and the oil-based ink compositions for forming a color imageobtained in (2) above.

TABLE 8 Result of Metallic Chromatic Black White Clear print ink colorink ink ink ink evaluation Example 1 S1 Y, M, C K W CL S Reference S1Y1, M1, C1 B1 W1 — AAA Example 9 Reference S2 Y1, M1, C1 B1 W1 — AAExample 10

(4) Print Evaluation Test

Ink sets were prepared by combining the metallic ink composition S1 (orS2) with the oil-based ink compositions for forming a color image, and aprint evaluation test was performed using two ink jet printers PM-4000PX(manufactured by Seiko Epson Corporation). For a first ink jet printer,a black ink composition, a yellow ink composition, a magenta inkcomposition, and a cyan ink composition were filled in correspondingcolor blocks. For a second ink jet printer, the metallic ink compositionS1 (or S2) was filled in a black block, the white ink composition wasfilled in a yellow block, and the clear ink composition was filled in alight cyan block.

Printing was performed at room temperature on photographic paper(glossy) having an ink-accepting layer (manufactured by Seiko EpsonCorporation, Product number: KA450PSK) as in a printing patterndescribed below. Furthermore, a sensory evaluation of the printedmatters was performed on the basis of an evaluation criterion describedbelow. The results are shown in Table 8.

Printing Pattern

Printing was performed using the metallic ink composition and a dryingprocess was performed. Subsequently, an image was printed on themetallic printed surface using the chromatic color ink compositions, theblack ink composition, the white ink composition, and the clear inkcomposition. In the sensory evaluation of a printed matter describedbelow, the evaluation was performed in an area where an image was formedusing the dye-containing ink compositions other than the white inkcomposition and the clear ink composition.

Sensory Evaluation Criterion of Printed Matter

S: Any metallic gloss ranging from a high metallic gloss to a mattetexture could be obtained, and in addition, any transparent, metalliccolor could be obtained.AAA: Any metallic gloss ranging from a high metallic gloss to a mattetexture could be obtained.AA: A metallic gloss on which a reflection of an object can be clearlyseen could be obtained.

As shown in Table 8, by employing the ink jet recording method using theabove ink set, a recorded matter in which transparency was improved andwhich had a metallic image having any color tone could be obtained.Specifically, unlike pigments, by using dyes, transparent printing couldbe performed, and sharp full-color printing having a color tone withoutturbidity could be obtained. In addition, by using a black ink, a smokytexture could be provided to a printed image. The colorless andtransparent clear ink could provide a function of protecting a metallicglossy surface. Furthermore, by using a white ink according to need, amatte texture could be partly provided on a metallic glossy surface.

1. An ink set comprising: an ink composition containing a metallicpigment; and at least one ink composition selected from the groupconsisting of a chromatic color ink composition containing a chromaticcolor dye, a black ink composition containing a black dye, and acolorless and transparent ink composition that does not contain acolorant.
 2. The ink set according to claim 1, wherein images havingmeasured values of no less than 200, 200, and 100 respectively, for thedegree of mirror surface gloss measured at 20°, 60°, and 85° as definedby JIS Z 8741 can be formed when the ink composition containing themetallic pigment is ejected on a recording medium.
 3. The ink setaccording to claim 1, wherein the recording medium is photographic paper(glossy) (product number: KA450PSK) manufactured by Seiko Epson.
 4. Theink set according to claim 1, further comprising: a white inkcomposition containing a white pigment.
 5. The ink set according toclaim 1, wherein the metallic pigment is composed of plate-likeparticles, when the major axis of the plate-like particles in a planethereof is represented by X, the minor axis thereof is represented by Y,and the thickness thereof is represented by Z, a 50% average particlediameter R50 of an equivalent circle diameter determined by the area ofthe X-Y plane of the plate-like particles is in the range of 0.5 to 3□m, and the metallic pigment satisfies the relationship R50/Z>5.
 6. Theink set according to claim 1, wherein the ink composition containing ametallic pigment further contains an organic solvent and a resin.
 7. Theink set according to claim 1, wherein the ink composition containing ametallic pigment contains the metallic pigment in an amount in the rangeof 0.1 to 10.0 mass percent.
 8. The ink set according to claim 6,wherein the organic solvent contains at least one alkylene glycol etherwhich is liquid at room temperature and atmospheric pressure.
 9. The inkset according to claim 6, wherein the organic solvent is a mixture of analkylene glycol diether, an alkylene glycol monoether, and a lactone.10. The ink set according to claim 6, wherein the resin is at least oneselected from the group consisting of polyvinyl butyral, celluloseacetate butyrate, polyacrylic polyols, polyurethanes, vinylchloride-vinyl acetate copolymers, and resin emulsions thereof.
 11. Theink set according to claim 6, wherein the ink composition containing ametallic pigment further contains at least one selected from acetyleneglycol surfactants and silicone surfactants.
 12. An ink jet recordingmethod comprising: ejecting droplets of an ink composition to cause thedroplets to adhere to a recording medium having an ink-accepting layer,wherein an image is formed using the ink set according to claim
 1. 13. Arecorded matter recorded by the ink jet recording method according toclaim
 12. 14. An ink jet recording apparatus comprising: the ink setaccording to claim 1.